How about Wuhan, Chongqing and chengdu. I once experience the Yangtze Tour offered by this website from Chongqing to Wuhan. It is also has upstream route from Wuhan to Chongqing. You can get to Wuhan from Shanghai and then get to Chengdu from Chongqing. Then, you can turn to trains from Chengdu to Xian. I wonder if there are cruise ships on on the river for cold winter. Perhaps you can also get to Kunming and Lijiang, Yangshuo and Guilin, then go to Xian in the end. Enjoy your trip!